Isoperla gravitans (Needham & Claassen 1925)

Isoperla gravitans (Needham and Claassen)
Clioperla gravitans, Needham and Claassen, 1925, 2:138. Holotype $: Olympia, Thurston Co., Washington, USA, (CU-Type is missing), (wings and male genitalia).
Isoperla gravitans, Hoppe, 1938, 4:156.
Clioperla gravitans, Claassen, 1940, 232:196.
Isoperla gravitans, Jewett, 1954, 11:548. Allotype 2: Youngs R., Clatsop Co., Oregon, USA, l/V/1940, S. G. Jewett (CAS), (female genitalia).
Isoperla gravitans, lilies, 1960:405.
Additional references: Isoperla gravitans, Jewett, 1959, (male and female genitalia).
Male. — Macropterous. Length of forewings 14-16 mm; length of body 12-15 mm. General body color medium brown. Head pattern consisting of dark "H"shaped mark in center, and lighter brown transverse bar across frons between eyes
dium brown pigment band and vermiculate markings (Fig. 105). Forewings light, veins dark brown. Femora, tibiae and tarsi dark brown; femora with light yellow band at distal end. Abdominal terga with 8 faint rows of longitudinal dots, 2 mesal and 3 each laterally. Cerci dark brown, bearing small fine hairs. Paraprocts short, stout, tapering to blunt points apically, broad at base, appearing triangular from above, recurving anteriorly barely over 10th tergum, and bearing medium fine hairs
rest of segment (Fig. 106). Ninth sternum and tergum much lighter than rest of abdominal segments. Aedeagus entirely membranous, tubular, apex expanded into large rounded lobe void of spinulae; small nipple at anterodorsal margin, large posteromesal lobe with "T"-shaped band of medium length spinulae and 2 spinulae free patches posteriorly (Figs. 109B & HOD); band of scattered fine spinulae encircling mesal section, interrupted before posteromesal lobe (Figs. 109D & HOC), wide band of small stout spinulae encircling aedeagus below posteromesal lobe (Figs. 109C & HOB), small patch of medium-length stout spinulae at posteroventral margin (Figs. 109A& 110A).

Isoperla gravitans és una espècie d'insecte plecòpter pertanyent a la família dels perlòdids.